


Bad Influence

by Mottlemoth



Category: Sherlock (TV)
Genre: Greg Lestrade's Filthy Mouth, Humour, M/M, Rated T for One Bad Word, Rosie Watson's First F-Bomb, Secret Relationship, Sherlock Holmes and John Watson are Parents, Uncle Mycroft, background Johnlock
Language: English
Status: Completed
Published: 2020-10-25
Updated: 2020-10-25
Packaged: 2021-03-08 17:54:20
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 923
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27190691
Author URL: https://archiveofourown.org/users/Mottlemoth/pseuds/Mottlemoth
Summary: Three-year-old Rosie Watson learns a fun new word; Sherlock is in no doubt who taught her it.
Relationships: Mycroft Holmes/Greg Lestrade
Comments: 28
Kudos: 405





	Bad Influence

**Author's Note:**

> This ficlet used to live in a single work with all my others, but I've decided to separate it out into a work of its own. Give me a shout if you ever find it posted somewhere it shouldn't be (i.e., off AO3). <3

The incident occurs at Baker Street, on the morning of John Watson's birthday.

In honour of the recent pleasantness between them, Mycroft has offered to pay for lunch at a country pub in Beaconsfield. Sherlock's new-found paternal inclinations have done him credit, and relations have been excellent since Rosamund's birth. Mycroft is eager for them to continue. He's even been entrusted with his niece's care once a week, Tuesday evenings now spent at Uncle Mycroft's house. Though Mycroft initially took on the duty rather nervously, he now finds it one of the most enjoyable parts of his week. Rosamund is a charming child, quick and headstrong.

She's also developing a talent for surprising them all.

On the point of leaving Baker Street for the pub, as Sherlock carefully fastens Rosie into her puffy purple coat, the toy elephant she intends to take slips from her tiny grasp. It hits the floor with a muffled clunk, dislodging its head from its body.

Rosamund looks down at it, and in a clear and exasperated voice sighs,

"Fuckin' 'ell."

Mycroft nearly swallows his tongue. John ejects the mouthful of cold coffee he was finishing as Sherlock blinks in staggered astonishment.

A bark of laughter sounds from the hallway.

_"Brilliant."_

Sherlock recovers first. As he slots Rosie's elephant back together for her, flushing, he shouts, "I'm not sure _brilliant_ is the correct response to the situation, Lestrade!"

"Are you kidding?" Greg reappears in the sitting room, grinning ear to ear with his car keys hooked around his fingers. "That was _fantastic._ I wish we'd been filming it. Christ, I'm gonna treasure that forever."

"And what other _fantastic_ vocabulary have you taught our three-year-old, might I ask?" Sherlock demands.

Greg gives him a startled look. "What makes you think it was me?"

Sherlock scoffs. "The London accent was a fairly reliable clue, for a start. And need we mention your proclivity for bad language?"

"Whoa, whoa—" Greg holds up his hands. "Steady on. London accent? She said two words, mate. You can't judge accent from that. And I hardly ever babysit her, do I? Once in a blue moon. My hands are clean here."

"And who else do you suggest would have taught her that particular turn of phrase?" Sherlock asks, furious.

Mycroft draws a silent breath.

Greg holds Sherlock's gaze for a few seconds, thinking about it, his tongue poked into his cheek.

"Alright," he admits at last. "It was me. Slipped out a few weeks ago—stubbed my toe on the door—I didn't think she'd heard me."

"Well, clearly she did," Sherlock snaps. "And now our toddler has the lexical inclinations of a docker. She's only just mastered the simple past tense, Lestrade. Now you've enlightened her in the fine art of profanity."

"Right. Sorry, Sherlock. Sorry, John. I'll get my mouth washed out with soap when we get to the pub."

"See that you do," Sherlock says, hoisting Rosie up into his arms. "I _knew_ you'd be a bad influence. Your irresponsibility staggers me. Perhaps you could try following Mycroft's example more closely? At least she has _one_ suitable role model..."

He sweeps out onto the landing, his head held high.

John, fighting a smile tooth-and-nail, casts Greg a look of mock disapproval then follows.

In the ensuing silence, Mycroft screws his toes into his shoes. The blush he managed to restrain comes flooding forth, burning through his face as he watches Lestrade turn towards him.

Greg raises both eyebrows, waiting.

Mycroft bites down into his lip. "Thank you," he murmurs.

Greg's smile breaks into a grin. 

"You owe me," he says. _"Big_ time."

"I most certainly do."

"Wouldn't do for them to discover that responsible Uncle Mycroft has been enlightening Rosie in _the fine art of profanity,_ would it?"

Mycroft's insides squirm. "I knew that she'd heard," he says, pained. "But I truly didn't think she'd remember. Heaven help me. It was _weeks_ ago."

"What happened?"

"I only stepped into my study for a moment to monitor my e-mails. I found a message to say a junior clerk had wiped a critical file, and somehow wiped the back-ups as well. I was... well, somewhat _annoyed._ Then when I turned around, I discovered Rosamund had followed me. She presumably heard my, ah... outburst."

"And picked up some choice new words, huh?" Greg hooks his thumbs into his belt, amused. "Well, Mycroft. That's what happens when you're a suitable role model."

"I'm so sorry," Mycroft says. "I should have revealed myself. It was wicked of me to let you. It's just been very pleasant, to be getting on so well with Sherlock after all these years—and Rosamund is very dear to me, and I'd hate to—"

"Oi," Greg interrupts him, soft. His eyes sparkle. "S'fine. I don't mind. Uncle Greg can take the flack on this one. John's clearly not that fussed. I'll just buy him a pint at the pub. Problem solved."

Mycroft's flush deepens. "And I shall buy you one," he promises.

Greg drops him a wink. 

"Buy me one next week when we're there on our own," he says. "I need to watch myself today if I'm gonna act like I've never seen the place before." He shakes his head, smirking. "All these lies I keep up for you, Holmes."

Mycroft's heart gives a squeeze. "I'm very grateful for your trouble, Lestrade."

Greg's eyes shine, deep and playful and dark.

"C'mon," he says, jangling his keys. "Let's see if you can act like you've never seen the backseat of my car."


End file.
